1. Field of the Invention
The present invention relates to a flat panel display, and more particularly to a method of controlling a picture quality of a flat panel display that is adaptive for automatically analyzing a shape, a size, and brightness of a display stain of indeterminate shape having an irregular pattern, and compensating brightness of the display stain of indeterminate shape on the basis of the analyzed result.
2. Description of the Related Art
Recently, there has been paid attention to various flat panel display devices which can reduce their weight and size that are a disadvantage of a cathode ray tube. The flat panel display devices include a liquid crystal display LCD, a field emission display device FED, a plasma display panel, and an organic light emitting diode OLED and the like.
The flat panel display device includes a display panel for displaying a picture. A display stain has been showed in a test process of the display panel. The picture quality defect has a different brightness or chromaticity compared to a normal display surface.
A display stain, which is found in a test process of the display panel, is primarily generated by a process deviation in manufacturing process. For example, a display stain is generated by an exposure deviation of a photo-resist due to an overlap of lenses and a lens aberration, etc in an exposure process. Such an exposure deviation of a photo-resist causes a deviation of a parasitic capacitance between gate electrode and drain electrode (or source electrode) of a thin film transistor TFT, which is formed by a photolithography process, a height deviation of a column spacer that maintains a cell gap, and a deviation of a parasitic capacitance between a signal line and a pixel electrode. As a result, an exposure deviation of a photo-resist causes a difference of brightness or chromaticity at a display image.
A display stain may be generated in a fixed shape such as dot, line, belt, block, circle, and polygon, etc., or in an indeterminate shape having an irregular pattern. The display stain of indeterminate shape, a shape as well as a difference of brightness or chromaticity is not uniform as shown in FIG. 1. In a display stain of indeterminate shape, it is difficult to automatically measure a pattern thereof and a degree of a stain. Thus, the display panel, which the display stain of indeterminate shape is found in a test process, goes into the discard due to a display stain of indeterminate shape, and the display stain of indeterminate shape make worse a yield.